The first drug to slow the destruction of the brain in Alzheimer's has been heralded as momentous and historic.
It’s a research breakthrough which ends decades of failure and shows a new era of drugs to treat the most common form of dementia is possible.
The drug lecanemab attacks the sticky gunge - called beta amyloid - that builds up in the brains of people with Alzheimer's.
But there are questions around its impact, side effects and use.